1. Field of the Invention
The present invention relates to a shielded-electric-wire connection part structure that is applied to various electric appliances such as a motor, that has been loaded on, for example, an electric car, a hybrid car, etc. and, more particularly, to a shielded-electric-wire connection part structure, with respect to which shield connection and waterproof are each reliably done.
2. Related Art
In a case where connecting a shielded electric wire, that serves as an electricity-supplying high-voltage electric wire or a control signal electric wire, to a motor that has been loaded on, for example, an electric car, a hybrid car, etc., it is demanded that electro-magnetic shielding or waterproofing be performed. This electro-magnetic shielding is performed in order to prevent the operation of the motor from becoming unstable due to various noises while waterproofing is performed in order to prevent the electric contact parts, etc. from being broken, etc. due to rain droplets, etc. that enters into the motor case by going forward along the shielded electric wire.
A shielded electric wire connection part structure, with respect to which those electro-magnetic shielding and waterproofing have been done, is disclosed in Japanese Patent Application Laid-Open No. Hei 10-112924. Explaining this concretely with reference to FIGS. 1, 2A and 2B, as illustrated in FIG. 1, the shielded-electric-wire connection part structure 1 connects a braid wire 6a of a shielded electric wire 6 to the interior of an electric wire insertion through-hole 2a of a motor case 2 serving as an appliance main body via a substantially circular-hollow-cylindrical housing 3, a bolt 4, and a shield connection ring 5 serving as a shield connector. Specifically, in a state where the outer-peripheral surface 3a at a forward end portion of the housing 3 is kept fitted in the electric wire insertion through-hole 2a of the motor case 2, an attaching flange 3b thereof is fastened and fixed by means of a bolt 4. And it is thereby arranged that the housing 3 having had the shielded electric wire 6 passed therethrough be attached to the motor case 2.
Also, as illustrated in FIGS. 2A and 2B, into the outer-peripheral recessed portion 3c at the forward end of the housing 3 is folded back the braid wire 6a of the shielded electric wire 6 that has been passed through the housing 3. This folded back braid wire 6a is clamped by a shield connection ring 5 that is fitted over the outer-peripheral recessed portion 3c at the forward end of the housing 3. This shield connection ring 5 is formed in the shape of a cap whose center is open, by the use of metallic material having excellent spring property. Whereby, the folded-back braid wire 6a of the shielded electric wire 6 is engaged with and retained by a plurality of spring piece portions 5a, that protrude outside, and engaging/retaining piece portions 5b so that the shield connection ring 5 may be freely drawn off or prevented from being drawn off from the braid wire 6a. Further, the respective spring piece portions 5a of the shield connection ring 5 are elastically contacted with the electric wire insertion through-hole 2a of the motor case 2. As a result of this, the braid wire 6a of the shielded electric wire 6 is earthed via the motor case 2.
Also, into an annular-recess like groove portion 3d that has been formed in the outer-peripheral surface 3a at the forward end portion of the housing 3 is fitted an O-ring 7 that provides an airtightness between the housing 3 and the motor case 2. Further, between an insulating outer clothing 6b of the shielded electric wire 6 and the housing 3 is interposed a substantially hollow-circular-cylindrical waterproof plug 8. It is thereby arranged that rain droplets, etc. be reliably prevented from entering into the motor case 2 from the outside. Also, the shielded electric wire 6 is inserted through the electric wire insertion through-hole 2a of the housing 2 in a state of its having been inserted through a corrugate tube 9. Further, a connection terminal not illustrated that is connected to a motor terminal portion not illustrated is bonded and connected to a core wire portion 6d that has been exposed from an insulating inner clothing 6c of the shielded electric wire 6.
It is to be noted that a similar technique regarding this shielded-electric-wire connection part structure 1 is disclosed in Japanese Patent Application Laid-Open No. Hei 9-180824.
However, in the above-described conventional shielded-electric-wire connection part structure 1, the electric wire insertion through-hole 2a of the motor case 2 and the braid wire 6a are connected to each other by the spring force of the shield connection ring 5. Therefore, there was the possibility that the seal performance would be deteriorated due to the setting of the spring property of the shield connection ring 5 resulting from the lapse of time, etc. Also, the same surface of the electric wire insertion through-hole 2a of the motor case 2 serves both as the shield surface for shielding the braid wire 6a of the shielded electric wire 6 and as the waterproof surface that the O-ring 7 contacts with. Therefore, when mounting the housing 3 onto the motor case 2 by the bolt 4, there was the possibility that the waterproof surface would be damaged with the result that the waterproofness became bad. Further, because the housing 3 is mounted on the motor case 2 via the flange portion 3b and the bolt 4, it becomes indispensable to ensure the mounting space. As a result, the entire structure became large in size.